This application is the national phase under 35 U.S.C. xc2xa7371 of PCT International Application No. PCT/JP98/00839 which has an International filing date of Feb. 27, 1998, which designated the United States of America.
The present invention relates to a novel non-aqueous secondary battery and a method of manufacturing the same
In recent years, development for high performance batteries have been proceeded positively along with demands for making electronic equipments to be reduced in the size and the weight and have multiple functions, and adaptable to a cordless system. Recently, lithium ion secondary batteries have, particularly, acquired wide markets more and more because of the light weight is reduced in spite of high voltage, high capacity and high power, compared with secondary batteries used generally so far such as lead storage batteries and nickel-cadmium batteries.
An electrode plate laminate of such a lithium ion secondary battery is usually manufactured by winding or laminating a sheet-like electrode of a predetermined shape cut out of a large sheet-like electrode together with a separator. The sheet-like electrode before cutting is generally manufactured by kneading active material particles together with a binder and a solvent into a slurry, coating he same on a metal foil (current collector sheet), then evaporating the solvent and fixing the active material particles on the metal foil.
Therefore, it may be a worry that active material particles near the end face (cut face) of the sheet-like electrode chip down during manufacture of the electrode plate laminate or upon containment of the laminate into a battery can, to cause internal short circuit with the fallen active material particles. As a result, this lowers the yield of the battery and increases the manufacturing cost.
An object of the present invention is to prevent the falling of the active material particles from the end face of the sheet-like electrode thereby preventing occurrence of internal short circuit caused by manufacturing steps.
Further, an electrode plate laminate of a conventional wound-type battery has been manufactured by spirally winding up strip-like positive electrode, negative electrode and separator. A polyethylene microporous film has been usually used for the separator and it is manufactured, for example, by forming fine pores in a film and then applying stretching.
In such a wound type battery, the width (size in the direction of a winding axis) and a length (winding length) of a separator are designed larger than those of the positive electrode and the negative electrode in view of deviation or the like during winding. Particularly, in the lithium ion secondary battery, the width and the length of the negative electrode are designed to be larger than those of the positive electrode with an aim of preventing short circuit at the ends of electrodes during charge/discharge (refer to Japanese Utility Model Registration No. 2506572).
Accordingly, in a lithium ion secondary battery in particular, since the substantial electrode area of the electrode plate laminate is equal to the entire area of the positive electrode active material layer, the size of the electrode plate laminate (size in the direction of the winding axis) is determined by the width of the separator and the width of the positive electrode is smaller than the width of the negative electrode which is further smaller than that of the separator, then, there is a limit for increasing the area of the positive electrode active material layer for an electrode plate laminate of an identical size. The battery capacity for the battery can of a same size may be increased by increasing the thickness of the active material layer for the positive and negative electrodes, but the film resistance increases as the thickness of the active material layer is increased to lower the output characteristics.
An object of the present invention is to increase the battery capacity of the electrode plate laminate contained in a battery can of a same size without increasing the thickness of the active material layer.
On the other hand, development has been proceeded recently for a sheet-type cell referred to as xe2x80x9cpolymer batteryxe2x80x9d that basically utilizes the principle of the lithium ion secondary battery. The positive electrode and the negative electrode of the polymer battery are constituted with the same material as that for the conventional lithium ion secondary battery, but a polymeric solid electrolyte serving both as a separator and an electrolyte, instead of a separator having an electrolyte solution permeability, is interposed between the active materials of both of the electrodes. Then, the polymer battery is manufactured by preparing a flat electrode plate laminate by integrating both of the electrodes and the polymeric solid electrolyte, putting the electrode plate laminate into a flexible casing and sealing the same without pouring the electrolyte solution.
In view of the material and the manufacturing method described above, it has been said that the polymer battery has advantages that the degree of freedom for the battery shape is relatively high, the thickness and the weight can be reduced and the safety is improved. However, since the ionic conductivity of the solid electrolyte is lower compared with the liquid electrolyte used in the lithium ion secondary battery, the polymer battery involves a problem in view of the discharging characteristics at a high current density compared with the lithium ion secondary battery.
Further, when a flat electrode plate laminate is prepared by integrating a conventional separator made of microporous film of polyolefin, instead of the solid electrolyte, between both of electrodes, putting the electrode plate laminate into a flexible casing, pouring electrolyte solution into the casing and sealing that thereby, manufacturing a lithium ion secondary battery, the battery is inferior to the conventional battery of using a metal battery can as a vessel in view of discharging characteristics at a high current density and cycle characteristics. This is attributable to that gaps are liable to be formed between the separator and the electrode since the urging pressure between the electrode and the separator is lower in the flexible casing compared with the metal battery can. Further, it is difficult to integrate the separator comprising the microporous polyolefin film with the electrode in order to prevent the formation of gaps.
As described above, a non-aqueous secondary battery equipped with a flat electrode plate laminate in a flexible casing having a relatively high degree of freedom for battery shape and thin thickness (sheet-type battery), and having characteristics equal to those of conventional lithium ion secondary batteries using the metal battery can as a casing has not yet been obtained.
An object of the present invention is to provide a non-aqueous secondary battery equipped with a flat electrode plate laminate in a flexible container having a relatively high degree of freedom for the battery shape and thin thickness, which is excellent in discharging characteristics at a high current density and cycle characteristics.
The present invention provides a non-aqueous secondary battery having, in a casing, an electrode plate laminate having at least a positive electrode and a negative electrode in which an active material layer is fixed to at least one surface of a current collector and a separator having an electrolyte solution permeability interposed between the active material layers of both of the electrodes, with a non-aqueous electrolyte solution being poured and sealed in the casing, wherein the separator is an aggregation layer of insulating material particles formed by bonding insulating material particles to each other by a binder and fixed to at least one of the positive electrode and the negative electrode, and an end face of at least one of the positive electrode active material layer and the negative electrode active material layer is at least partially coated with the aggregation layer of insulating material particles. The battery is referred to as a first battery according to the present invention.
According to this battery, the chipping down of the active material from the end face of the active material coated with the aggregation layer of insulating material particles can be prevented. Further, short circuit caused by the deformation for the shape of the electrode end face upon being given shock such as by falling down the battery can be prevented. Further, since the coating material is an aggregation layer of insulating material particles having an electrolyte solution permeability, the following effects can be provided.
That is, when the end face of the active material layer is coated with the aggregation layer of insulating material particles having the electrolyte solution permeability, for example, in a non-aqueous secondary battery having an electrode plate laminate prepared by laminating one or more of integrated layers formed by integrating both of the electrodes and a separator, since the aggregation layer of insulating material particles coated at the end face can constitute a path of an electrolyte solution that is entered and released by the expansion and contraction of the electrode active material caused upon charge/discharge, the cycle characteristics are excellent compared with the case of coating by an insulating material having no electrolyte solution permeability.
Further, when the end face of the active material is coated with the aggregation layer of insulating material particles having the electrolyte solution permeability, since the electrolyte solution can be impregnated after the manufacture of the electrode plate laminate, it is advantageous in view of manufacture compared with the case of coating by an insulating material having no electrolyte solution permeability.
Coating of the aggregation layer of insulating material particles may be applied as far as the end face of the current collector.
The insulating material particles constituting the aggregation layer of insulating material particles may be organic or inorganic materials as shown below.
The inorganic materials can include, for example, oxides such as Li2O, BeO, B2O3, Na2O, MgO, Al2O3, SiO2, P2O5, K2O, CaO, TiO2, Cr2O3, Fe2O3, ZnO, ZrO2 and BaO, zeolite, nitrides such as BN, AlN, Si3N4 and Ba3N2, silicon carbide (SiC), carbonates such as MgCO3 and CaCO3, sulfates such as CaSO4 and BaSO4, and zircon (ZrO2.SiO2), mullite (3Al2O3.2SiO2), steatite (MgO.SiO2), forsterite (2MgO.2SiO2) and cordierite (2MgO.2Al2O3.5SiO2) as a sort of porcelains.
The organic materials can include, for example, resin particle such as of polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polymethyl methacrylate, polyacrylate, fluoro resin such as polytetrafluroethylene and polyvinylidene fluoride, polyamide resin, polyimide resin, polyester resin, polycarbonate resin, plyphenylene oxide resin, silicone resin, phenol resin, urea resin, melamin resin, polyurethane resin, polyether resin such as polyethylene oxide and polypropylene oxide, epoxy resin, acetal resin, AS resin and ABS resin.
Among the insulating material particles, inorganic material particles are preferred and oxide particles are particularly preferred.
The method of forming the aggregation layer of insulating material particles includes a method of dispersing insulating material particles and a binder in a solvent, coating that to a surface for forming the aggregation layer of insulating material particles and then evaporating the solvent.
The binder usable herein can include, for example, latexes (for example, styrene-butadiene copolymer latex, methyl methacrylate-butadiene copolymer latex and acrylonitrile-butadiene copolymer latex), cellulose derivatives (for example, sodium salt and ammonium salt of carboxymethyl cellulose), fluoro rubber (for example, copolymer of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene) and fluoro resins (for example, polyvinylidene fluoride and polytetrafluoroethylene). Among them, a fluoric binder such as fluoro rubber or fluoro resin is preferred.
The amount of the binder is preferably from {fraction (1/500)} to ⅗, more preferably, from {fraction (1/500)} to xc2xd and, further preferably, from {fraction (1/500)} to ⅕ of the insulating material particles by volume ratio.
Further, the solvent can include, for example, ethyl acetate, 2-ethoxyethanol (ethylene glycol monoethyl ether), N-methyl pyrrolidone (NMP), N, N-dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), tetrahydrofran (THF) and water.
Coating for the end face of the sheet-like electrode with the insulating material may be conducted either before or after the formation of the electrode plate laminate. If it is applied after forming the electrode plate laminate, since mechanical strength at the end face of the electrode plate laminate is increased, pressing fabrication at the upper portion of the battery can after assembling into the battery can is facilitated. Further, this can save assembling of insulating plates to upper and lower portions of the battery can.
When the end face is coated before forming the electrode plate laminate, the thickness T for coating 3F is made greater than or equal to the thickness Tk for the active material layers 1b and 2b (it is made equal to the entire thickness of the sheet-like electrodes 1, 2), as shown, for example, in FIG. 20 so as to cover at least the entire end face of the active material layers 1b and 2b. Further, it is so adapted not to overhang both sides in the direction of the thickness of the sheet-like electrodes 1 and 2.
The width W of the coating is not restricted particularly so long as it is such a width as substantially protecting the active material layer and, in a case of using an existent battery can, the maximum value is determined depending on the size thereof.
Further, the present invention also provides a non-aqueous secondary battery having, in a casing, an electrode plate laminate having at least a positive electrode and a negative electrode in which an active material layer is fixed to at least one surface of a current collector and a separator having an electrolyte solution permeability interposed between the active material layers of both of the electrodes, with a non-aqueous electrolyte solution being poured and sealed in the casing, wherein an end face of at least one of the positive electrode active material layer and the negative electrode active material layer is at least partially coated with the aggregation layer of insulating material particles, the positive electrode active material layer is formed to such a size as not overhanging the negative electrode active material layer paired therewith as a cell layer, and the separator is an aggregation layer of insulating material particles formed by bonding insulating material particles to each other by a binder and fixed to at least one of the positive electrode and the negative electrode, and is disposed so as to cover at least the entire surface of the positive electrode active material layer opposed to the negative electrode and so as not to overhang the end face of the current collector. The battery is referred to as the second battery according to the present invention.
In this battery, at least a portion of the end face of the positive electrode active material layer is preferably coated with the aggregation layer of insulating material particles.
Further, in this battery, the electrode plate laminate preferably comprises one or more of laminated integrated layers each of which is prepared by interposing an aggregation layer of insulating material particles formed by bonding insulating material particles to each other by a binder as a separator between active materials of both of the electrodes and by integrating the separator with both of the electrodes. The battery is referred to as a fourth battery according to the present invention.
In this battery, the separator is constituted with the aggregation layer of insulating material particles in which the insulating material particles are bonded to each other by the binder. In the aggregation layer of insulating material particles, a plurality of insulating material particles may be disposed in the direction of the film thickness, or only one of them may be disposed in the direction of the film thickness so long as the insulating material particles are disposed densely within a film plane.
That is, in the aggregation layer of insulating material particles, gaps between each of the insulating material particles bonded by the binder form voids to permeate ions in the electrolyte solution to pass therethrough, and presence of the insulating material particles inhibits short circuit between the positive electrode active material layer and the negative electrode active material layer. Further, since the gaps between each of the insulator particles are continuous both in the direction of the film thickness and in the direction of the film plane in the aggregation layer, the electrolyte solution is allowed to permeate easily into the positive and negative electrode active material layers.
Since the battery performance of the non-aqueous electrolyte secondary battery such as a lithium ion secondary battery is lowered by the intrusion of water, it is necessary to arrange the circumstance for the entire manufacturing steps such that the water does not intrude, or the electrode plate laminate be dried before pouring the electrolyte solution into the battery can. Upon drying, since the conventional microporous film made of polyolefin resin has low heat resistance, heat shrinkage is caused to the film or the voids are crushed to result in a problem of deteriorating the battery characteristics unless drying for the electrode plate laminate is conducted, for example, in vacuum at a low temperature such as about 80xc2x0 C. Therefore, the drying needs an extremely long time or the degree of drying is insufficient to result in a worry of water intrusion into the electrolyte solution.
However, since the aggregation layer of insulating material particles formed by using oxides or the like as the insulating material particles is excellent in the heat resistance compared with the microporous film made of polyolefin resin, it can be dried even at a temperature higher than or equal 100xc2x0 C., so that the foregoing problems can be solved. This can be said to be particularly effective in a case of using, as a positive electrode, lithium manganese composite oxides which is said to be highly sensible to the undesired effects particularly by the intrusion of the water content.
The thickness of the separator comprising the aggregation layer of insulating material particles has no particular restriction and it is preferably from 1 xcexcm to 100 xcexcm and, more preferably, from 10 xcexcm to 50 xcexcm.
In this battery, the positive electrode active material layer is formed to such a size as not overhanging the negative electrode active material layer paired therewith as a cell layer. That is, in each of the cell layers, the area of the surface of the positive electrode active material layer is made equal to the area of the surface of the negative electrode active material layer or smaller than the same. Then, separator is fixed to at least one of the positive electrode and the negative electrode and disposed so as not to overhang the end face of the current collector.
Therefore, the outer size of the electrode plate laminate is determined depending not on the size of the separator but on the size of the negative electrode. Accordingly, if an electrode plate laminate of an identical size is manufactured, the size of the negative electrode and the positive electrode can be increased than conventional one.
Further, since the separator is disposed so as to cover at least the entire surface of the positive electrode active material layer opposed to the negative electrode, short circuit between the positive electrode and the negative electrode can be prevented.
In this battery, when the electrode plate laminate has an insulating layer interposed between the current collectors of both of the electrodes, it is preferred that the insulating layer is fixed to at least one of the positive and negative current collectors, and disposed so as to cover at least the entire surface of the positive electrode current collector opposed to the negative electrode current collector and so as not to overhang the end face of the current collector.
That is, when an electrode laminate plate comprises a positive electrode and a negative electrode each having an active material layer fixed only on one surface of a current collector, and the positive and negative current collectors are opposed not via the active material layer (for example, in a wound-type using each one of a positive electrode and a negative electrode having an active material layer on one surface), it is necessary to insulate between the positive and negative current collectors on the side not fixed with the active material layer. Since ionic permeability is not required for the portion, it may suffice that an insulating layer with no ionic permeability is interposed and it is preferred that the insulating layer is fixed to at least one of the positive and negative current collectors in the arrangement described above. Further, the insulating layer may also be constituting with the aggregation layer of insulating material particles.
Further, present invention provides a non-aqueous secondary battery having, in a casing, an electrode plate laminate having at least a positive electrode and a negative electrode in which an active material layer is fixed to at least one surface of a current collector and a separator having an electrolyte solution permeability interposed between the active material layers of both of the electrodes, with a non-aqueous electrolyte solution is poured and sealed in the casing, wherein the electrode plate laminate comprises one or more of laminated integrated layers each of which is prepared by interposing an aggregation layer of insulating material particles formed by bonding insulating material particles to each other by a binder as a separator between the active materials of both of the electrodes and by integrating the separator with both of the electrodes, and the casing is a flexible casing. The battery is referred to as a third battery according to the present invention.
When the electrode plate laminate is constituted with an integrated layer formed by integrating the separator and both of the electrodes as described above, no deviation is caused between each of the positive electrode, the separator and the negative electrode upon manufacture of the electrode plate laminate. Further, deviation is not caused when shock or the like is applied after inserting the electrode plate laminate into the casing and sealed. In addition, since the inter-electrode distance does not change, deterioration of characteristics is less caused during charge/discharge at a high current density, and degradation of cycle characteristics can also be reduced.
The method of integrating the separator, namely, an aggregate of the insulating material particles to the surface of the active material layers of both the positive electrode active material layer and the negative electrode active material layer can include, for example, the following three methods.
As the first method, a mixture of insulating material particles and a binder are at first dispersed in a solvent to form a slurry, which is coated on the surface of the active material layer of at least one of the electrodes. Immediately, the other of the electrodes is stacked on this surface such that both the electrode active material layers are opposed via the slurry. Subsequently, they are heated to evaporate the dispersion medium.
As the second method, the slurry described above is at first coated on the surface of the active material layer of at least one of the electrodes and then dried to form a separator layer. Then, the other of the electrodes is stacked such that the active material layers of both of the electrodes are opposed to each other via the separator layer. Subsequently, they are hot pressed to be bonded with each other at such a temperature that the binder is melted.
As the third method, the liquid dispersion described above is at first coated on the surface of the active material layer of at least one of the electrodes and then dried to form a separator layer. Then, a solvent capable of dissolving the binder is coated on the separator layer. Then, the other of the electrodes is stacked such that the active material of both of the electrodes is stacked such that the active material of both of the electrodes are opposed to each other via the separator layer. Then, they are bonded to each other by pressing and drying.
The casing of the battery is a flexible casing and the material therefor is preferably such a material that vapors of water and the non-aqueous solvent can not substantially permeate and that is thin and light in weight to such an extent as not deteriorating the battery performance. They include, for example, metal sheets such as iron sheet, stainless steel sheet and aluminum sheet, and resin sheets such as of polyethylene, polypropylene, ionomer resin, copolymer of ethylene and vinyl alcohol, nylon resin, aromatic polyamide resin, aromatic polyester resin, polyethylene terephthalate resin, polyethylene naphthalate resin, polyphenylene oxide, polyoxymethylene, polycarbonate, polytetrafluoroethylene resin, and polyvinylidene fluoride resin and, if necessary, two or more of such sheets in lamination or two or more of ingredients of sheets mixed or polymerized together may also be used.
The battery according to the present invention has a feature in the structure of the electrode plate laminate as described above and other constituent materials for the battery (for example, electrolyte solution and materials for positive electrode and negative electrode) can be constituted in accordance with the prior art.
Then, constituent materials for the lithium ion secondary battery using the non-aqueous electrolyte is to be explained.
The positive electrode active material used in the lithium ion secondary battery can include lithium composite metal oxides capable of intercalating and deintercalating lithium in an ionic state such as LixMI(1xe2x88x92y)MIIyO2 (0 less than xxe2x89xa61.1, 0xe2x89xa6yxe2x89xa61, MI and MII each represents at least one element selected from Co, Cr, Mn, Fe and Ni), LixMn(2xe2x88x92y)MyO4 (0 less than xxe2x89xa61.1, 0xe2x89xa6yxe2x89xa61, M represents at least one element selected from Li, Al, Cr, Fe, Co, Ni and Ga).
The negative electrode active material used in the lithium ion secondary battery can include carbonaceous materials such as coke, graphite and amorphous carbon and metal oxides and alloys including Si, Ge, Sn, Pb, Al, In, Zn and the like capable of intercalating and deintercalating lithium in an ionic state.
The electrode active material described above is mixed with a binder and a solvent to form a slurry, coated on the current collector and then dried to obtain an electrode, and examples of the binder in this case can include, for example, latexes (for example, styrene-butadiene copolymer latex, methyl methacrylate-butadiene copolymer latex and acrylonitrile-butadiene copolymer latex), cellulose derivatives (for example, sodium salt and ammonium salt of carboxymethyl cellulose), fluoro rubber (for example, copolymer of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene) and fluoro resins (for example, polyvinylidene fluoride and polytetrafluoroethylene). Examples of the solvent can include ethyl acetate, 2-ethoxyethanol (ethylene glycol monoethyl ether), N-methyl pyrrolidone (NMP), N,N-dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), tetrahydrofran (THF) and water.
As the non-aqueous electrolyte used for the lithium ion secondary battery, for example, LiPF6, LiBF4, LiClO4, LiAsF6, CF3SO3Li and (CF3SO2)2N.Li dissolved solely or as a combination of two or more of them in an organic solvent can be used.
The organic solvent in the non-aqueous electrolyte solution can include, for example, propylene carbonate, ethylene carbonate, xcex3-butyrolactone, dimethyl sulfoxide, dimethyl carbonate, ethylmethyl carbonate, diethylcarbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane and tetrahydrofurane, which may be used each alone or in admixture of two or more of them (for example, a mixed solvent of a solvent of high dielectric constant and a solvent of low viscosity).
The concentration of the electrolyte in the non-aqueous electrolyte solution is preferably from 0.1 to 2.5 mol/l.
Further, the present invention provides a method of manufacturing a non-aqueous secondary battery, which comprises forming a negative electrode member by fixing a negative electrode active material layer to at least one surface of a sheet-like negative electrode current collector, fixing an aggregation layer of insulating material particles formed by bonding insulating material particles to each other by a binder on the surface of the negative electrode member, then cutting the negative electrode member into a predetermined shape depending on the kind of the battery, thereby preparing a negative electrode having the aggregation layer of insulating material particles fixed thereon as a separator having an electrolyte solution permeability, and forming an electrode plate laminate by using the negative electrode and a positive electrode of a predetermined shape having a positive electrode active material layer fixed to at least one surface of a sheet-like current collector, such that the positive electrode active material layer does not overhang the negative electrode active material layer paired therewith as a cell layer. The method is referred to as a first manufacturing method according to the present invention.
According to this method, an electrode plate laminate of a non-aqueous secondary battery of the present invention, in which the positive electrode active material layer is formed to such a size as not overhanging the negative electrode active material layer paired therewith as a cell layer, and the separator is an aggregation layer of insulating material particles formed by bonding insulating material particles to each other by a binder, fixed to at least one of a positive electrode and a negative electrode and disposed so as to cover at least the entire surface of the positive electrode active material layer opposed to the negative electrode and so as not to overhang the end face of the current collector can be manufactured easily and efficiently.
The electrode plate laminate includes a wound type of cutting a positive electrode, a negative electrode and a separator each into a strip-like shape and then spirally winding them by a winding machine, a zigzag-folded type of cutting them each into a strip-like shape and stacking them in parallel by folding back at a predetermined width and a simple lamination type of cutting them into a circular or square shape and piling them.
Accordingly, when the wound type electrode plate laminate is formed by the method described above for example, the positive electrode is cut such that the width thereof is smaller than the width of the negative electrode, and conducting winding such that a negative electrode active material layer not opposing to the positive electrode active material layer is disposed at a starting portion and an ending portion for winding.
When a zigzag-folded type electrode plate laminate is formed, for example, the positive electrode is cut such that the width thereof is smaller than that of the negative electrode, and they are folded such that a negative electrode active material layer not opposing to the positive electrode active material layer is disposed at a starting portion for folding and an ending portion for folding. When a simple lamination type electrode plate laminate is formed, for example, the positive electrode is cut such that the outer circumferential profile thereof is smaller than that of the negative electrode and then they are stacked with their center being aligned with each other.
Further, the present invention provides a method of manufacturing a non-aqueous secondary battery, which comprises forming a positive electrode member by forming a positive electrode active material layer to at least one surface of a sheet-like positive electrode current collector, within the size of the current collector determined for an electrode plate laminate, such that a margin is present at the periphery, forming an aggregation layer of insulating material particles formed by bonding insulating material particles to each other by a binder to the positive electrode member so as to cover the surface and the end face of the positive electrode active material layer, then cutting the positive electrode member integrated with the aggregation layer of insulating material particles in perpendicular to the plane of the sheet at the position for the margin to prepare a positive electrode having the aggregation layer of insulating material particles fixed thereon as a separator having an electrolyte solution permeability, and forming an electrode plate laminate by using the positive electrode and a negative electrode of a predetermined size having a negative electrode active material layer fixed to at least one surface of a sheet-like current collector, such that the positive electrode active material layer does not overhang the negative electrode active material layer paired therewith as a cell layer. The method is referred to as a second manufacturing method according to the present invention.
According to this method, an electrode plate laminate of a non-aqueous secondary battery of the present invention, in which at least a portion of the end face of the positive electrode active material layer is coated with the aggregation layer of insulating material particles, the positive electrode active material layer is formed to such a size as not overhanging the negative electrode active material layer paired therewith as a cell layer, and the separator is an aggregation layer of insulating material particles formed by bonding insulating material particles to each other by a binder, fixed to the positive electrode and disposed so as to cover at least the entire surface of the positive electrode active material layer opposed to the negative electrode and so as not to overhang the end face of the current collector can be manufactured easily and efficiently.
Further, the present invention provides a method of manufacturing a non-aqueous secondary battery, which comprises forming a positive electrode member by forming a positive electrode active material layer to at least one surface of a sheet-like positive electrode current collector, within the size of the current collector determined for an electrode plate laminate, such that a margin is present at the periphery, forming an aggregation layer of insulating material particles formed by bonding insulating material particle to each other by a binder to the positive electrode member so as to cover the surface and the end face of the positive electrode active material layer, then integrating a negative electrode member having a negative electrode active material layer on at least one surface of a sheet-like negative electrode current collector on the aggregation layer of insulating material particles with the negative electrode active material layer being faced thereto and then cutting the integrated positive electrode member and the negative electrode member in perpendicular to the plane of the sheet at the position of the margin, thereby forming an integrated layer which is formed by interposing an aggregation layer of insulating material particles as a separator having an electrolyte solution permeability between the active materials of both of the electrodes and integrating the separator and both of the electrodes, and laminating the integrated layer by one or more layers to form an electrode plate laminate. The method is referred to as a third manufacturing method of the present invention.
According to this method, an electrode plate laminate of an non-aqueous secondary battery of the present invention, in which at least a portion of an end face of the positive electrode active material layer is coated with the aggregation layer of insulating material particles, the positive electrode active material layer is formed to such a size as not overhanging the negative electrode active material layer paired therewith as the cell layer, the separator is an aggregation layer of insulating material particles formed by bonding the insulating material particles to each other by a binder, fixed to the positive electrode and disposed so as to cover at least the entire surface of the positive electrode active material layer opposed to the negative electrode and disposed so as not to overhang the end face of the current collector, and the electrode plate laminate is formed by laminating one or more of integrated layers which is prepared by integrating both of the electrodes and the separator between the active material layers of both of the electrodes can be manufactured easily and efficiently.
Furthermore, the present invention provides a method of manufacturing a non-aqueous secondary battery, which comprises forming a positive electrode member by forming a positive electrode active material layer to at least one surface of a sheet-like positive electrode current collector, within the size of the current collector determined for an electrode plate laminate, such that a margin is present at the periphery, forming an aggregation layer of insulating material particles formed by bonding insulating material particles to each other by a binder to the positive electrode member so as to cover the surface and the end face of the positive electrode active material layer, then forming a negative electrode active material layer on the aggregation layer of insulating material particles, and then cutting that in perpendicular to the plane of the sheet at the position of the margin, thereby forming an integrated layer which is formed by interposing an insulation material particle aggregation layer as a separator having an electrolyte solution permeability between the active materials of both of the electrodes and integrating the separator and both of the electrodes, and laminating the integrated layer by one or more layers to form an electrode plate laminate. This method is referred as a fourth manufacturing method according to the present invention.
In this embodiment, the negative electrode active material can be functioned as an electrode without a current collector and, when a current collector or the like is fixed to the negative electrode active material layer after drying, a material, for example, a lath mesh (expanded metal having a thickness equal to that of usual current collector) which can be secured to the negative electrode active material layer by press bonding or the like may also be used.
According to this method, an electrode plate laminate of a non-aqueous secondary battery of the present invention, in which at least a portion of the end face of the positive electrode active material layer is coated with the aggregation layer of insulating material particles, the positive electrode active material layer is formed to such a size as not overhanging the negative electrode active material layer paired therewith as a cell layer, the separator is an aggregation layer of insulating material particles formed by bonding the insulating material particles to each other by a binder, fixed to the positive electrode and disposed so as to cover at least the entire surface of the positive electrode active material layer opposed to the negative electrode and so as not to overhang the end face of the current collector, and the electrode plate laminate is formed by laminating one or more of integrated layers prepared by integrating both of the electrodes and the separator between the active material layers of both of the electrodes can be manufactured easily and efficiently.